Apparatus for making pipe bends and the like



June 17, 1941. w. E. ZOELLER APPARATUS FOR MAKING PIPE BENDS AND THELIKE Filed July 13, 1937 e Y 00 E TZ N N. R W o T Mr T .l w A J M lPatented June 17, 1941 APPARATUS FORIPAfiKING PIPE BENDS AND III! WalterErzoeller, Louisville, Ky., assignor to Tube-Tums, Incorporated,Louisville, Ky, a corporation or Kentucw Application July 13, 1937,Serial No. 153,308

8 Claims. (Cl. 153-48) This invention relates to improvements inapparatusi'or manufacturing curved tubes from straight tube stock by theuse of an internal mandrel. Apparatus of this general type is shown inthe United States patent to Bohling 1,648,161. In the use of suchapparatus the upsetting and expanding action of the metal taking placein the production of tubular bends, coils, helices, serpentines and thelike from tubular pipe stock requires high pressures for forcing thestock over a stationary mandrel or for drawing a movable mandrel,through a stationary piece of stock. Although this operation customarilytakes place with both the stock and the mandrel highly heated,nevertheless pressures in the order of 3000 pounds per square inch arerequired at times for the satisfactory operation of the machine used forforming the final product.

Due to the use of this high pressure certain operating problems arise inthe commercial usage of such apparatus. One such problem arises Jecauseof the packing required for the pressure head of a machine of the naturedisclosed by the said Bohling patent. When an external rod or othermember extends from a pressure chamber relatively movable with respectto such member, and filled with an operating medium at high pressure,the resulting joint necessitates the use of special packing means andrequires constant supervision to prevent gradual leaking of the mediumunder pressure or the actual forcing out of such packing under the highpressure.

Furthermore when reloading the external rod with tubular stock, it hasbeen necessary to disconnect the mandrel and to support the rod by meansof a crane or the like, thus causing a bending movement of the rod aboutthe head of the cylinder through which it extends. This bending actioneven when only of a minor degree tends to loosen the high pressurepacking in the cylinder head and adds to the disadvantage above noted.

It has also been necessary to load the tubular stock upon the mandrelrod from the mandrel end. This inherent limitation requires removal ofthe hot mandrel, a relatively slow loading of tube stock while awaitingthe withdrawal of the machine cylinder, and then a replacing and relifeof the same as more specifically described hereinafter, and hasincreased the cost of manufacturing the product.

It will be noted that the presence of a mandrel rod within the movablecylinder diminishes the efiective working area contacted by the pressurefluid. Thus prior machines have required either a larger cylinder or ahigher working pressure in order to accomplish the same amount of workas could be secured were the mandrel rod located externally of thecylinder.

By means of the present invention each of the above disadvantages havebeen overcome.

to work efiiciently in a zone much cooler than that in which he iscompelled to work with the type of machine heretofore used where theloading has been at the hot region adjacent the mandrel and the heatingnozzle area.

Another object of the invention is to permit the mandrel element toremain fastened to the mandrel rod at all times and be retained in a hotenvironment during the entire cycle of operation in order to eliminateweaknesses resulting from repeated temperature changes in the region ofthe critical temperature of the mandrel metal.

A further object is to provide a machine of the type referred to inwhich the entire exposed interior area of the cylinder is acted upon bythe pressure medium.

Another important object of the invention is to provide a method ofshaping tubes over a mandrel by combined pressure and heat wherein themandrel is maintained in a heated condition at all times.

Another object is to permit, and facilitate a more rapid loadingoperation.

A further object is to provide means whereby a plurality ofmanufacturing operations may be conducted simultaneously from a singlesource of power.

Another object is to eliminate the trouble heretofore encountered in thepacking means.

Other advantages and objects, such as the increased efllciency ofoperation by savings in time of operation and amount of labor, theincreased capacity of the apparatus and the improved working conditionsfor the operator, will become more apparent when considered inconjunction with the accompanying drawing in which:

Fig. 1 is a side elevation showing the general Fig. 1,

assembly of one apparatus which may be used in carrying out thisinvention,

Fig. 2 is a plan view'of the structure shown in Fig. 3 is a section onthe line 3-3 of Fig. 1, and a Fig. 4 is a perspective view of one formof connecting means for the stationary rods.

In the form illustrated, an elongated press bed I is supported by aplurality of standards 2 intermediate its ends and provides a supportingtrack upon which the power mechanism for moving the tube sections overthe shaping mandrel may be mounted. At one end the press bed may bemounted upon a support 3 serving as an anchoring means for the mandrelrods and plunger rod later to be described. If desired, the opposite endof such press bed may -be so arranged as to provide a guide means forthe movable hood or oven structures shown generally at 4.

A power mechanism of the general type shown in the Bohling Patent1,648,161, may be mounted upon the press bed I for the purpose of movingthe tube stock over the mandrels and thus forming bent tubes accordingto the process disclosed in Bohling Patent 1,353,714. Such a machine maycomprise a movable cylinder 5 having supports 6 slidable along the pressbed I. Within the cylinder is a stationary piston 'I from which extendsa stationary hollow plunger rod 8 rigidly fastened at one end to thesupport 3. Any suitable arrangement of conduits or passages may beplaced or formed within such piston, plunger rod and support fordelivering a pressure fluid into and from the spaces within the movablecylinder 5 upon either side of the stationary piston so as to force thecylinder endwise in either direction.

The working end of said cylinder is completely closed in accordance withthis invention by a pressure tight head 9 which has a bracket carryingrods I0 secured to a pusher plate II.

One form of such pusher plate is shown in Fig. 3 wherein a pair of openslots I2 is provided for the reception of mandrel rods I3 later to bedescribed. As the purpose of the plate is primarily to force tubularstock along the mandrel rods and over the mandrels, it is obvious thatnumerous variations in size and shape of the plate as well as thelocation and number of the mandrel rod slots therein may be employedwithout departing from the teaching of the invention. The slots I 2 mayextend horizontally in from opposite edges if the mandrel rods are to bedisengaged laterally, or may extend at an inclined angle if the rods areto be lifted as well as moved transversely, or may extend down from thetop edge if the mandrel rods are to be lifted.

Securely fastened to the support 3 in any suitable manner is a pluralityof stress rods I4 extending forwardly, parallel to the path of movementof cylinder 5. While two such rods are shown herewith it is obvious thata single rod or any number of rods may be so employed. These stress rodsare preferably constructed of high tensile strength material, and sincethey are normally of appreciable length will ordinarily be flexible to alimited degree. Suitable bracket Ii may be provided for holding the rodsgenerally in position during the period in which no stress is appliedthereto. At their forward ends the stress rods I 4 are provided with anysuitable means whereby they may be readily attached to or detached fromthe mandrel rods I 3, and for holding the stress and mandrel rods .headand block may be integrally and permanently fastened to the ends oftheir respective rods I3 and I4. Various other fastening arrangementsmay be employed, for instance, a screw coupling or a turn buckle withits ends threaded on the mandrel and stress rods.

The location of the connecting means employed will normally be shortlybeyond the piston and a short distance to the rear of pusher plate'IIwhen the cylinder is in fully retracted position.

The mandrel rods I3, over which the tubular stock is to be moved for thepurpose of forming therbent tubes, extend forwardly from the connectingmeans. Such mandrel rods are customarily of somewhat greater length thanthe displacement stroke of cylinder 5 and carry at their forward endsthe mandreis 20' securely affixed thereto. Intermediate of their ends,rods I3 are supported within slots I2 in the pusher plate II, and upon asupporting structure 2| including rollers adapted to embrace, guide andsupport the pipe stock which is slid along the mandrel rod by the pusherplate.

When it is desired to load a mandrel rod from the rear end, the saidrear end is disengaged from the stress rod and swung at a slight angle.Such support 2| then functions as a fulcrum about which the elongatedmandrel rod and its attached mandrel element may be pivoted. If theswinging movement of the mandrel rod be in a vertical plane and the rearend of the rod be lifted through any considerable angle, the mandrel orthe tube thereon may engage the bottom of the oven 4 so that said bottomacts as the fulcrum support.

It is contemplated that the mandrel rods may swing about these supportrolls and out of the slots I2 in the pusher plate II to bring the freeend to any convenient loading position. The direction of swing willdepend upon the location and direction of the slots. If they swingvertically the rear ends of the mandrel rods may be raised into aconvenient loading position, as for example adjacent to an elevatedplatform or a second floor. In such a case the pipe stock could he slidthereon by gravity, thus providing a simple and rapid loading operation.When it is desired to reload, the motive fluid flow is reversed to movethe cylinder 5 and pusher plate II rearwardly, and by the time thedisengagement of stress and mandrel rods takes place and the mandrelrods have been swung to loading position, the rearwardly moving plate I0 has reached such a point as will allow the new load of tubes to slidealong the mandrel rod and against the tube which is still held betweenthe rolls of support 2|. Moreover the swinging of the mandrel rods movesthem out of slots I 2 of the plate so that the rods are unobstructed bysuch plate.

It the rods be swung horizontally and horizontal slots I2 are used inpusher plate II, the loading could be conducted from a convenientlocation of stock upon the same floor as the machine location. By usingany proper design and location of support 2|, the mandrel rod andattached mandrel can be held in proper displaced position relative tonormal working position whereupon no adjustment of the mandrel rodeither longitudinally or radially is necessary upon starting thesubsequent working cycle. However, should the mandrel rod, the attachedmandrel and the tube stock carried thereby deviate from this exactposition. it is a simple matter to realign the same after the stress andmandrel rods are again connected.

Heretofore alternate heating of the mandre l to a high temperature and acooling thereof/to a relatively low temperature have occurred Tn eachcycle of operation. These mandrels are customarily constructed of alloymetals having a critical temperature range through the limits of whichthe temperatures employed in the normal usage of the process frequentlyvary. This variation of temperatures of the mandrel metal through thecritical range causes a relatively rapid degradation of the metal andresults in the formation of small cracks, loss of proper shape and ageneral weakening of the metal. In addition the mandrel is beingsubjected to high working stresses as the tube stock is forcibly pushedthereover, and due to these factors the useful life of these expensivemandrels has .been relatively short.

By means of this invention the ovens 4 may be designed with sufilcientdepth and/or width so as to contain the mandrel and the partially formedbend thereon during the loading operation. The burner 22 may continue tosupply heat at an appropriate rate to, keep the mandrel within suitabletemperature limits during this period, and in so doing thus diminish thedegradation of the metal and thus prolong the mandrel life.

By employing an external pushing connection between cylinder and exteralmandrel rods, the mandrel rod formerly connected to the stationarypiston within the movable cylinder is completely eliminated with theresult that a troublesome packing joint is now unnecessary. Since theworking end of cylinder 5 may employ pressures in the order of 3000pounds per square inch a material saving in cost and maintenance is thuseffected. Furthermore, the omission of the mandrel rod from the workingspace increases the capacity of the machine by the amount equal to theproduct of the pressure employed times the area formerly occupied by thecross-section of such rod.

At the end removed from the working section of the cylinder 5 aconventionalpacking gland assembly 23 serves to pack the plunger rod 1and to prevent leakage from cylinder 5 during rearward movement thereof.Since the rearward movement of such cylinder is made without appreciableload, the pressures applied thereto are substantially less than thoseused on the working stroke and little difliculty with the packing gland23 is had. The plunger 1 serves to hold the internal piston in placewithin cylinder 5, and due to engagement with'the rear of cylinder 5also serves to guide and stablize the movement of the cylinder along thepress bed I and over the interiorly disposed piston. Consequently, thereactions of the forces exerted upon the movable cylinder during theloaded forward stroke and the unloaded rearward stroke are transmitteddirectly through plunger 5 to support 3.

Due to these several advantages resulting from the invention it isobviously preferably to load the mandrel rods from the rear. However, inthis connection it is to be expressly understood that if desired themandrel rods may be loaded from the front end without departing from thepipe stock may be loaded directly upon the open ends of mandrel rods l3during the retraction of the cylinder 5, after which the entire sequenceof these operations may be repeated in reverse and the new cycle ofoperation started.

It is thought that the sequence of operations will be apparent, but maybe briefly summarized as follows:

When the mandrel rod is nearly empty the operator directs the pressurefluid into cylinder 5 on the right of the stationary internal piston andpermits escape of the pressure fluid entrapped on the left of saidpiston. Cylinder 5 and pusher plate l0 then begin their rearwardmovement which may be accelerated if desired by any suit! ablearrangement. At this same time the operator may cut down the heat supplythrough burner 22 as desired, or may allow this heat supply to remainunchanged.

When the rod connecting means shown in Fig. 4 is employed the operatorthen moves the rear ends of the mandrel rods I3 to disengage them fromthe stress rods, This disengaging operation may be expeditiouslyefiected in a matter of seconds. It will be noted that all tensilestresses on these rods are relieved at this time since cylinder 5 ismoving backward without load. Upon bei'ng disengaged the rear end of themandrel rods may be tilted in accordance with the angle of slots I! inplate II and thus be disengaged therefrom and brought to loadingposition, the stress rods meanwhile lying loosely in brackets l5. Whilethis operation is taking' place cylinder 5 and plate II have movedrearwardly sumciently far to enable the pipe stock to he slid along themandrel rods by gravity or by pushing motion. By the time the mandrelrods are reloaded completely the plate II has been retracted to theposition shown in Fig. 1. The loaded rods are dropped into position inslots 3| of the plate III with the 'rear of the final pipe stockterminating a short distance ahead of the plate ll.

When the loaded mandrel rods are dropped into place in slots 12 themandrels 20 are again raised by this leverage to their former positions.Stress rods H are then sprung outwardly slightly to engage recesses l8of connectors I8 with the head IQ of mandrel rods l3. The resiliency ofstress rods H, the working clearance in connectors l6 and the ability ofthe mandrel rods l3 to move longitudinally through support 2| willenable the operator to accomplish this reconnection in a short period oftime. The controls for the pressure fluid are again reversed andcylinder 5 starts to move upon its working stroke. Preferably thisinitial movement is throttled somewhat so that the pusher plate II willengage the pipe sections without shock and enable the operator to alignany of the separate pipe sections which may be slightly out of alignmenton mandrel rods I3.

After aligning all pipe sections the operator admits the pressure fluidat full operating pressure to cylinder 5 and the manufacturing operationdisclosed in said Bohling patents then takes place. It will be notedthat at this time the reaction forces of the pressure fluid acts uponthe stationary internal piston and through stationary plunger rod 8 backupon support 3 in one direction, while at the same time the pusher plateH. acts against the pipe stock and against mandrels 20 in the oppositedirection. The force on mandrels 20 exerts an equivalent action upon themandrel rods i 3 and the rigidly connected stress rods I 4 upon support3 in a direction opposite to the reactive force of plunger rod 8 andthus maintains the stresses of the entire structure internal withinitself. In so doing, all-advantages of the Bohling inventions areretained while at the same time the enumerated advantages of the presentinvention are added thereto.

Having thus described my invention, what I claim as new and desire tosecure by Letters Patent is:

1. A machine for shaping tube sections, including a mandrel rod having adie mandrel at one end thereof, a supporting structure, means detachablysecuring the other end of said rod to said structure, a fulcrum supportfor said rod interposed intermediate the mandrel and the securing meanswhereby the detached mandrel rod may be pivotally moved on the fulcrumsupport 1 to a raised and accessible loading position while tube stockis loaded thereon from said other end, said mandrel support acting tosupport the mandrel at a point spaced from said securing means when themachine is in operation, a movable power element mounted upon saidsupport ing structure, and means connected to said power element forforcing tubular stock along said rod and over said mandrel when saidmandrel rod is in loaded position.

2. An apparatus for shaping tube sections, including an endwise movablecylinder, an anchorage at one end, a piston in said cylinder and securedto said anchorage, a plurality of stress rods parallel to and outside ofsaid cylinder and secured to said anchorage, a plurality of mandrelseach having a tube stock carrying rod in alignment with and detachablysecured to a corresponding stress rod whereby said mandrel rods whendetached may be loaded with tube stock from the rear end, means forheating said mandrels, and a pusher plate secured to said cylinder andslidable along all of said mandrel rods for forcing the stock over themandrels.

3. In an apparatus for shaping tube sections, a reciprocable actuatingmeans, a stationary stress rod extending parallel with and externally ofthe actuating means, a mandrel rod adapted to carry tube sections, anenlarged mandrel at one end of said mandrel rod and over which the tubesections are forced by the actuating means, heating means for saidmandrel, connecting means joining the other end of the loaded mandrelrod to the stress rod and means on said actuating means cooperating withthe loaded mandrel rod and serving to push the tube sections over theheated mandrel when the actuating means is moved in one direction.

4. In an apparatus for shaping a plurality of tube sectionssimultaneously, a reciprocable actuating means, a plurality ofstationary stress rods extending parallel with and externally of theactuating means, a plurality of ,mandrel rods adapted to carry tubesections, an enlarged mandrel at one end of each of said mandrel rodsand over which the tube sections are forced by the actuating means,heating means for said mandrels, connecting means joining the other endof the loaded mandrel rods to the stress rods and pushing means on saidactuating means cooperating with the loaded mandrel rods and serving topush the tube sections over the heated mandrels when the actuating meansis moved in one direction.

5. A machine for shaping tube sections, including tiltable mandrel rodhaving a die mandrel at one end thereof, a supporting structure, meansdetachably securing the other end of said rod to said structure andcomprising the sole means for securing said rod to said structure andholding it against endwise movement, a fulcrum support for said rodwhereby the detached rod adjacent to said mandrel may be pivotally swungto loading position when the securing means is detached, and will besupported in loaded position when said rod is attached by said securingmeans, a movable power element mounted upon said supporting structure,and means connected to said power element for forcing tube stock alongsaid rod and over said mandrel when said mandrel rod is in loadedposition and said securing means is functioning.

6. A machine for shaping tube sections, including a tiltable mandrel maybe pivotally swung drel at one end thereof, a supporting structure, amovable power element mounted upon said supporting structure, meansconnected to said power element for forcing tubular stock along said rodand over said mandrel, means detachably securing the end of said rod tosaid supporting structure at a point closely adjacent to the rearmostposition of said forcing means whereby said rod may be detached from thesupporting structure at said point and tilted into stock receivingposition, or may be held rigidly in a position parallel with the line ofmovement of said first mentioned means, and comprising the sole meansfor securing said rod to said structure, and a fulcrum support for saidrod whereby the detached mandrel rod may be pivotally held on thefulcrum support with its detached end in a raised and accessible loadingposition while tube stock is loaded thereon.

'7. A machine for shaping tube sections, including a tiltable mandrelrod having a die mandrel at one end thereof, means for heating saidmandrel, a supporting structure, a movable power element mounted uponsaid supporting structure, means connected to said power element forforcing tubular stock along said rod and over said mandrel, meansdetachably securing the other end of said rod to said supportingstructure whereby said rod may be detached from the supporting structureat said point and tilted into stock receiving position, or may be heldrigidly against endwise movement and in a position parallel with theline of movement of said means connected to the power element, saidsecuring means comprising the sole means for securing said rod to saidstructure, and a fulcrum support for said tiltable rod and independentof said power element, whereby the detached mandrel rod may be pivotallyheld by the fulcrum support with its detached end in a raised andaccessible loading position while tube stock is being loaded thereon andthe power element is being moved away from the heating means, andwithout removing the mandrel from the heating means.

8. A machine for shaping tube sections, including a tiltable mandrel rodhaving a die mandrel at one end thereof, means for heating said mandrel,a supporting structure, a movable power element mounted upon saidsupporting structure, means connected to said power elesaid rod to saidstructure, and a fulcrum located between said power element and saidheating means and arranged so that the detachable mandrel rod may bepivotaily held by the fulcrum support with its detached end in a raisedand means comprising the sole means for securing 10 accessible loadingposition while tube stock is being loaded thereon and the power-elementis being moved away from the heating means, and without removing themandrel from the heating means.

WALTER E. ZOEILER.

